The proposed research is to synthesize a 2-D array of proteins with various peptide sequences on a solid substrate on demand, using a nozzleless, directional droplet-ejector array and MEMS (microelectromechanical systems) technology. The proposed research is to lay down the underlying technologies for a portable and affordable system for synthesis of protein probe arrays on a solid substrate. The synthesis system for protein probe array is to make protein chip technology available to individual laboratories so that the laboratories may be able to immobilize thousands of peptides on a solid substrate for bioassay and screening, and have far greater flexibility in chip design and faster turnaround in fabricating new chips. The envisioned portable protein synthesis system is based on a nozzleless, directional ejector array and MEMS technology to enable the rapid and facile synthesis of a two-dimensional array of any protein sequence on a porous or nonporous planar substrate using small quantities of proteinogenic amino acids. The envisioned "PECM" (Protein Ejector Chip Machine) is designed for use in any biological research laboratory;it will be no more difficult to operate than a standard protein synthesizer. The proposed technique is entirely different from the technology that produces protein probes pre-made at factory, and completely different also from microarray techniques that spot pre-made protein sequences. The PECM uses novel microfluidic management techniques and an array of self-focusing acoustic transducer (SFAT) for ejecting the 20 proteinogenic amino acids in any desired sequence to any location in order to form a 2-D array of protein probes on a solid chip. The PECM will be a flexible, compact and low cost system that consists of a 2-D array of SFAT ejectors along with microfluidic components, a wash station, a printed circuit board (that contains the control and pulsed-sinusoidal-wave-generation circuits), servomotors and mechanical fixtures, all integrated on a single platform. To demonstrate proof-of-principle, an array of 10 x 10 sets of 20 directional SFAT ejectors will be integrated with MEMS-based microfluidic components for producing 100 protein probes of amino acids of arbitrarily specified sequence on a cellulose membrane functionalized with appropriate linker/spacer chemistry. A single location on the membrane will be inked by 20 directional SFAT ejectors that can eject droplets in any direction off from the straight vertical direction so that a spot can be inked by 20 ejectors without any mechanical motion of the ejectors. Consequently, the envisioned PECM will have few moving parts and non- stringent alignment requirements. PUBLIC HEALTH RELEVANCE: The proposed research will demonstrate 2-D array synthesis of proteins with various peptide sequences on a solid substrate, using a directional ejector array to eject nanoliter droplets of proteinogenic amino acids on demand. The research is to lay down a firm technical foundation for a portable, flexible and affordable protein synthesis system that will produce any protein probe array on a solid substrate (from small amounts of proteinogenic amino acids). With the envisioned protein synthesis system, proteomics scientists will be able to generate protein probes on a chip in any way they desire (at their sites within hours), as they carry out bioassays.